The heart is the center of human circulatory system that pumps blood through our body. It is a muscle that pumps the blood only in one direction. In order for the heart to effectively maintain this unidirectional flow of blood, it must have properly functional valves that prevent back flow through its system, or regurgitation. The heart is divided into four chambers, right and left atria, and right and left ventricles. The four chambers are connected to the aorta, the inferior and superior vena cava, the pulmonary artery, and the pulmonary veins.
The mitral valve (“MV”) separates the left atrium from the left ventricle while the tricuspid valve (TV) separates the right atrium from the right ventricle. The aortic valve (“AV”) is located between the left ventricle and the aorta while the pulmonary valve (“PV”) is located between the right ventricle and the pulmonary artery.
Generally, valves should open and close completely with every heart beat or contraction. Incomplete opening and closing of the valves cause improper flow of blood, either back flow and/or reduced. These are valvular diseases. The valvular diseases are divided into two categories, regurgitation and stenosis. Regurgitation is a failure of valve to close completely allowing back flow of blood. Stenosis is a failure of valve to open completely reducing the flow of blood. Both can increase stress on the heart.
Mitral valve regurgitation (“MVR”) is a valvular disease in which an incomplete closure of the MV results in a back flow of blood. Such back flow of blood increases stress on the heart which can decrease the heart function and eventually lead to an irregular heart beat or a cardiac arrhythmia.
Traditional treatment of a worsening MVR requires an open heart surgery with a sternotomy or a thoracotomy then opening the heart itself following a cardiopulmonary bypass and a cardiac arrest. Once the chest is opened and access to the heart is gained, the MV is either repaired or replaced with an artificial valve. Although very effective, this open-heart procedure is an invasive high-risk surgery accompanied by a substantial morbidity and mortality. The mortality due to the surgery itself can be as high as 5%. Hence, the procedure is often reserved only to those patients with severe symptomatic MVR.
This high morbidity rate of the open heart surgery has recently lead to an increase in research to develop a safer and relatively more simple alternative procedures to repair the MVR using a cardiac catheterization technique. Along this international effort to find a safer alternative procedure, recently, this inventor presented internationally his thesis regarding “the mitral valve cerclage coronary sinus annuloplasty” and demonstrated outstanding result of the MVR treatment involving the application of a circular pressure around the mitral annulus (MA). This thesis has been filed through PCTas an international patent application (application number: PCT/ US2007/023836), and is currently published with the international patent office (publication number: W02008/060553), which are incorporated herein in their entirety.
The aforementioned thesis and published patent applications disclose the mitral valve cerclage annuloplasty procedure. Briefly explained, a catheter is placed at the coronary sinus after accessing the right atrium through the jugular vein, and then a cerclage suture is passed through the proximal septal vein. This cerclage suture can easily pass through the right ventricular outflow tract (“RVOT”). The inventor defines this technique as “the simple mitral cerclage annuloplasty.” Then the cerclage suture can be easily pulled into the right atrium thus placing the cerclage suture circumferentially around the MA. Once positioned, tension is applied to the cerclage suture and tightens the mitral valve. This brings together the two leaflets of the MV so that they are approximated to each other thus decreasing the size of its incomplete closure. This procedure can obtain a very similar result when compared to the result of a conventional surgery that directly tightens the mitral annulus, and can immediately reduce the regurgitation effectively treating a MVR.
However, there were technical problems in the previous thesis and patent applications that needed to be solved. First, there is a need to have a tension locking device that can apply a proper tension and maintain it securely during the procedure. Second, since this tension is maintained with a very fine cerclage suture i.e., 0.014 inch nylon cerclage used in the researches (although thickness may change), it can cause damages on the cardiac tissues where the suture contacts and exerts its pressure.
To address these technical problems, this inventor has filed Korean patent application (application number 2009-0080708) on Aug. 8, 2008, titled “the Mitral Valve Cerclage Annuloplasty Apparatus” that includes the coronary sinus and the tricuspid valve protection device, and a knot delivery device.
This patent application has also been filed with the U.S. Patent and Trademark Office and patent offices in other countries.
In the aforementioned patent application, the cardiac tissue is protected from the damage caused by the direct suture contact using a tissue protective device comprising a coronary sinus tube (“CS tube”) and a tricuspid valve tube (“TV tube”). Further, a knot delivery device is used to place a knot at the end of the tissue protective device to complete the procedure.
However, even though the knot was placed at the end of the tissue protective device, a slack of suture remained between the end of the tissue protective device and the knot, so that the proper tension needed on the cerclage was difficult to obtain initially, and due to the remaining excess suture, the cerclage became loose.
In the aforementioned mitral valve cerclage annuloplasty procedure, when the cerclage suture became loose, the tension on the suture decreased thereby reducing its circumferential pressure applied around the MA resulting in a decreased effectiveness of the MVR treatment. This invention is intended to provide a viable solutions to overcome these problems.